Jenkins is a leading automation server that supports two types of pipelines to define CI/CD workflows: Declarative and Scripted. Although they serve the same purpose, they are significantly different in syntax, usability, and features. In this blog, we will dive into the core differences between Declarative and Scripted pipelines, discuss their use cases, and provide examples to help you choose the right approach for your projects.
What is a Jenkins Pipeline?
Jenkins pipeline: it's the flow of automatic steps that outline how the software moves from source code to deployment. Pipelines are written in Groovy-based Domain Specific Language (DSL) and, because of that, they can be written as code, which provides version control and easier collaboration.
The Jenkins pipeline is divided into:
- Declarative Pipeline
- Scripted Pipeline
Declarative Pipeline
Declarative pipeline is a more structured and user-friendly way of defining pipelines. It is designed to give a simpler and more predictable syntax that reduces the complexity of pipeline creation.
Key Features of Declarative Pipeline:
- Simplified Syntax: Uses a top-level pipeline block, which makes the structure easy to understand.
- Strict Syntax Rules: Makes sure specific blocks like stages, steps, and post are present to ensure consistency.
- Validation: Declarative pipelines are easier to validate and debug because of their rigid structure.
- Built-in Options: Supports built-in tools like agent, triggers, and post conditions.
Example:
pipeline {
agent any
stages {
stage('Build') {
steps {
echo 'Building.'
}
}
stage('Test') {
steps {
echo 'Testing.'
}
}
stage('Deploy') {
steps {
echo 'Deploying.'
}
}
}
post {
success {
echo 'Pipeline succeeded!'
}
failure {
echo 'Pipeline failed!'
}
}
}Scripted Pipeline
The Scripted pipeline is the original and more flexible pipeline type in Jenkins. It allows Groovy scripting with full freedom, enabling advanced and complex pipeline definitions.
Key Features of Scripted Pipeline:
- Groovy Syntax: Makes use of the full Groovy scripting capabilities.
- Dynamic Behavior: It supports dynamic generation of stages and steps.
- High Flexibility: Ideal for complex workflows that require advanced customization.
Example:
node {
stage('Build') {
echo 'Building.'
}
stage('Test') {
echo 'Testing.'
}
stage('Deploy') {
echo 'Deploying.'
}
}Main Differences
| Feature | Declarative Pipeline | Scripted Pipeline |
|---|---|---|
| Syntax | Structured and stiff | Groovy-based and flexible |
| Ease of Use | Beginner-friendly | Groovy knowledge required |
| Validation | Easier to validate | More error-prone |
| Flexibility | Limited | High |
Pipeline Selection
Use Declarative Pipeline if:
- You are new to Jenkins or Groovy
- Your pipeline has a simple, structured, and predictable flow
- Readability and maintainability matter to you
Use Scripted Pipeline if:
- Advanced scripting requirements are needed
- Your workflow has dynamic or complex logic
- You are comfortable with Groovy scripting
Conclusion
Both Declarative and Scripted pipelines have their own strengths and limitations. Declarative pipelines are ideal for most standard use cases due to their simplicity and structure, while Scripted pipelines are indispensable for projects that demand high flexibility and customization.
Knowing the differences and use cases, you can effectively harness the power of Jenkins pipelines, making your CI/CD workflows more efficient and getting software to market faster. Select the approach that best fits your project's complexity and your team's experience.